GB1411596A - Phosphate coated polymeric articles having a sealable topcoating - Google Patents

Abstract

1411596 Coated polymeric articles E I DU PONT DE NEMOURS & CO 21 Sept 1972 [22 Sept 1971 19 July 1972] 10301/75 Divided out of 1411592 Heading B2E An organic polymeric article is provided with a continuous, non-crystalline gas-barrier coating on at least one surface thereof in amount 0.02 g/m<SP>2</SP> comprising aluminium orthophosphate or iron orthophosphate wherein the atom ratio of metal to phosphorous is 2.3-0.5, and a sealable topcoating over at least one coated surface, which top coating contains a vinylidene chloride polymer and an epoxy resin. Up to 50% of the aluminium atoms in the orthophosphate may be replaced by tin, titanium and zirconium, and from up to 20% of the aluminium atoms in the orthophosphate may be replaced by zinc, chromium and magnesium providing that if tin, titanium or zirconium atom replacement also exists then only a total of up to 50% of the aluminium atoms are replaced. The articles may be coated by applying a dispersion preferably prepared by first dissolving in the desired medium a source of iron or aluminium ions separately dissolving a source of phosphorous ions and then combining the solutions to form the orthophosphate. Metals other than aluminium or iron can be added e.g. as halides of the metal. When sources of metal are used that result in a formation of chloride ions, the chloride ions are removed e.g. by dialysis or by means of an ion exchange resin. Coating compositions may also contain additives such as resins that improve the wettability and adhesion of the coating e.g. melamine-formaldehyde resins, ureaformaldehyde resins, polyethylene imine, and amino acids such as glycine and alanine or in combination. The compositions can be applied by kiss coating, doctor rolls, gravure rolls, immersion, spraying. The articles may be films, containers, bottles, fibres prepared from polyesters, polypropylene, polyethylene and copolymers thereof including ionomers, a perfluoro polymer prepared from tetrafluoro ethylene and hexafluoropropylene, polyacrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polystyrene, polyimides, polyamides, cellulose acetate, regenerated cellulose. Preferred articles are polyester film such as oriented heats at polyethylene terephthalate and oriented linear polyproylene films. The articles may be pretreated by flame, electrical discharge treatement, or acid or alkaline etching. The coated film can be primed before application of the scalable topcoat. Priming agents include silanes, polyurethanes, aqueous solutions of melamine-formaldehyde resins and aluminium chlorohydroxide. The top coating can be applied by solvent coating, melt extrusion, hot lamination of a preformed film of the heat sealable polymer.